The broad, long-term objectives are: to increase our knowledge of basic psychobiological processes in storage and retrieval of information; to provide a behavioral "preparation" for furthering our understanding of the pathology of memory, including that resulting from minor homeostatic disturbances; and to extend a retrieval-oriented model of memory to the domain of the extinction of aversively motivated behaviors, thereby gaining information potentially relevant to behavior therapies for phobic disorders as well as to learning theory. The specific aims of assessing various modulations of memory are addressed in three major areas of proposed research: 1) Analysis and investigation of the consequences of the forgetting of stimulus attributes. This includes studies on time-dependent changes in generalized interference from training and contextual stimuli; on the potential role of "new learning" in producing certain reminder effects; on the retention of interoceptive cues; and o changes in the associative control over drug tolerance. 2) Investigation of aspects of retrieval processes in amnesia. Issues to be examined here include the transfer of control of memory retrieval to new cues; the dynamics of inaccessible (but recoverable) memory; and the relationship between various homeostatic disruption and anterograde amnesias. 3) Application of a memory retrieval schema to an analysis of extinction of aversively motivated behavior. Can manipulations designed to reactivate memory of a traumatic episode during an extinction exposure enhance the elimination of fear? Studies are proposed in which the level of memory reactivation is varied during response-prevention ("flooding") in active avoidance and during CS-alone exposure in Pavlovian fear conditioning. This approach provides a new direction for research of the elimination of fear motivated responding.